Automated multiple-sample processors designed as multiple-sample collectors are used to automatically take samples of fluids, i.e. liquids or gases. The automatic nature of this process makes it possible for samples to be taken even in inaccessible locations; for example, water samples can be taken in the deep sea, known as “water sample collectors” (WSC). Experiments of this kind at the sample location generally involve an enclosed water volume being defined by a benthic chamber and a sample then being drawn in the chamber. A multiple-sample collector allows a plurality of samples to be taken simultaneously, but also sequentially at predefined temporal intervals (fixed, yet time-resolved sampling). Key aspects of the technical implementation of multiple-sample collectors of this kind are the sampler itself and the automatic drive during sampling. The invention relates in particular to piston pumps as samplers, the pistons of which can be displaced by a spring drive. A spring drive allows automatic triggering without a direct power supply. Said supply is then only required to trigger the springs, but has suitably smaller dimensions than a direct drive, and therefore the multiple-sample collector can be operated, in a self-sufficient manner, for a longer period of time at an inaccessible location by means of a battery supply. There are various solutions in the prior art.
U.S. Pat. No. 6,840,121 B2 discloses for example a self-sufficient, self-powered multiple-sample collector for fluids, in particular liquids, in which ten piston pumps in the form of syringes are vertically arranged in a cylindrical support frame. Each piston is preloaded by means of a compression spring. Upon triggering, the spring is relaxed and in so doing pulls the piston back such that liquid is sucked in through a needle-shaped opening in the syringe.
Spiral springs (or helical springs) can be designed as compression springs (helical compression springs) or as extension springs (helical extension springs). Compression springs can be subjected to pressure and pushed together under pressure (absorption of potential energy). When this pressure is relieved, they relax and can do work (release of the stored potential energy). Extension springs can be subjected to tension and are pulled apart under tension (absorption of potential energy). When this tension is relieved, they are pulled together and can do work (release of the stored potential energy).
Piston pumps or syringes are also known in particular for use in aquatic environments from the multiple-sample collectors disclosed for example in U.S. Pat. No. 6,187,530 B1 and in the brochure entitled “Spritzenprobennehmer K/MT 115-Meerestechnisches Gerät zur Wasserprobennahme” from K.U.M Umwelt-und Meerestechnik Kiel GmbH. In this document, the pistons of the syringes are displaced by motorized means rather than in a spring-operated manner, however.
Various multiple-sample collectors comprising piston pumps are described in the following cited documents. In U.S. Pat. No. 4,116,067 A, the end of the piston that is remote from the piston pump is guided in a spiral-shaped slot such that rotating the piston pump in the slot plane results in the piston being displaced. In U.S. Pat. No. 4,288,206 A, the pistons are displaced by motorized means, in that they are fastened to a common bearing beam which is moved vertically upwards and downwards by means of an eccentric. In WO 96/30 740 A2, the piston is displaced by means of a vertical spindle. US 2010/0247378 A1 discloses a piston pump which is used both to receive fluid and to dispense fluid; the piston is displaced by motorized means in this case. U.S. Pat. Nos. 5,201,720 A, 5,800,405 A and WO 2012/085 580 A1 disclose piston pumps each having two spiral springs for displacing the piston. US 2006/0069 354 A1 discloses a piston pump in the form of a syringe, in which the piston is loaded by means of four compression springs, with each two compression springs working against one another such that they tension one another in a reciprocal manner.
U.S. Pat. No. 3,884,081 A describes an automated multiple-sample processor designed as a multiple-sample collector for air, comprising four piston pumps in the form of syringes which have a sample opening, a cylindrical housing and an axially displaceable piston and which are removably mounted in a support frame. Each piston is connected to an unguided spiral spring, which is designed as an extension spring and is supported in the support frame, by means of the free end of said piston that is remote from the needle opening as the sample opening. In the tensioned initial position, the extension spring is pulled apart and locked, and the piston is retracted into the cylindrical housing of the syringe. The lock has a release lever that can be actuated by a driver on a rotatable shaft. The rotatable shaft is connected to a motor drive. When the release lever is actuated by the driver, the fixed extension spring is unloaded, is pulled together and displaces the piston by pulling it out of the cylindrical housing of the syringe. At the same time, an air sample is sucked in through the needle opening located in the medium to be sampled. A particularity of this known multiple-sample collector is that the needle opening is closed at the same time as the air sample is drawn in order to securely confine the drawn air sample.